A wide range of neurological diseases and disorders exist that are not well addressed by present medical technology. Among these, dysphagia (a swallowing disorder that affects the central nervous system thereby weakening neuromuscular control and effectively reducing the ability to properly swallow) is a particularly life threatening disorder placing persons at risk of aspiration pneumonia. Patients at risk of aspiration pneumonia have a 17% survival rate over three years (Pick et al., 1996). Estimates are that over 7 million persons in the U.S. have dysphagia as a result of neurological diseases or disorders such as stroke, traumatic brain injury, brain tumors, Parkinson's disease, multiple sclerosis (Humbert, Lynch and Ludlow, in preparation 2008) and other neurological diseases and over 300,000 persons develop a swallowing disorder as a result of a neurological disease or disorder in the United States each year. Over 50% of patients with neurological diseases or disorders are at risk of aspiration pneumonia because of loss of central nervous system control of their swallowing resulting in either delayed or reduced elevation of the hyolaryngeal complex, which does not allow them to prevent food or liquid from entering the airway (Lundy et al., 1999). Normally the hyoid and larynx are raised by about 20 mm during swallowing producing an inversion of the epiglottis and assisting with opening of the upper esophageal sphincter.
Frequently, patients having dysphagia require 24-hour attention to prevent aspiration and ensure that the passage of food and/or fluids, particularly saliva, into the respiratory system is minimized. It has previously been shown that glass rod pressure stimulation to the faucial pillars in the mouth can trigger swallowing (Pommerenke, 1927) while chemical blocks of laryngeal sensation severely impair volitional swallowing in normal adults (Jafari, Prince, Kim, & Paydarfar, 2003). Pharyngeal stimulation can initiate laryngeal closure and elevation for swallowing in animals (Jean, 1984), while laryngeal stimulation will trigger a swallow (Nishino, Tagaito, & Isono, 1996). In humans, when sensory stimulation of the oropharynx is presented during a period separate from swallowing, it enhances cortical activity in the swallowing regions (Fraser et al., 2003; Hamdy et al., 2003; M. Power et al., 2004; Lowell et al., 2008), but does not benefit subsequent swallowing in dysphagic patients (M. L. Power et al., 2006). These approaches to stimulation, however, generally involve the placement of a device or probe into the oral cavity which interferes with eating food and liquids and can alter oral sensory function in patients already having oral sensory deficits.
Accordingly, there is a need for therapeutic methods and a device for enabling those who are afflicted with dysphagia or other conditions or disorders that affect the ability to properly swallow without interfering with oral function or altering oral sensory function.